The invention relates to an x-ray diagnostic installation comprising a timing device for determining the fluoroscopy time, as well as comprising programming and display means for the preselection and display of selected instantaneous values for a fluoroscopic examination.
A known x-ray diagnostic installation of this type (Siemens brochure: Optimatic System for De-Centralized Programmed Radiography, pages 16 and 17, order No. MR 65/1207) is equipped with rotary type switches for preselection of the tube voltage and of the tube current. Their instantaneous values are brought to display during fluoroscopy via dial (or scale-and-pointer) instruments, so that it is possible to read off the instantaneous radiation exposure of the patient. A mechanical short-term timer serves the purpose of determining the fluoroscopy time. It indicates the residual time still remaining, respectively, and interrupts the x-ray tube current circuit upon expiration of the fixed fluoroscopy time for the purpose of terminating the fluoroscopy operation. If the voltage and current values remain constant, then it is possible to directly read them off as mean (or average) values during the fluoroscopy.
In the case of an x-ray diagnostic installation comprising an automatic dose regulation, in which the parameters of the x-ray tube are constantly varied, in the known x-ray diagnostic installation, a determination of the mean value and thus an ascertainment of the x-ray dose to which the patient is exposed is very difficult.